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Study on the Interaction Between Leucyl-tRNA Synthetase and tRNALeu from Escherichia Coli
Received date: 2002-11-07
Online published: 2003-01-18
Supported by
supported by the National Natural Science Foundation of China (39730120) and the Chinese Academy of Sciences (Grant KJ951-B1-610) supported by the 863 project in China (103-13-02-01)
The aminoacyl-tRNA synthetases (aaRSs) catalyze the esterification of amino acidsto their cognate tRNAs. They are specific for both amino acid and tRNA substrates to ensurethe high fidelity required by translation. Leucyl-tRNA synthetase (LeuRS) in one of aaRSsand belongs to class Ⅰ aaRSs. In order to investigate the interaction between LeuRS andtRNALeu, it was necessary that large amount of in vivo tRNALeu were isolated and various mu-tants of tRNALeu was obtained in vitro. In the present work Escherichia coli tRNALeu1 andtRNALeu2 were overproduced in Escherichia coli MT102 and isolated from the transformants,respectively. The kinetic constants of LeuRS for the tRNALeu were the same with previous da-ta. The leucine accepting ability of the unmodified tRNALeu1 and tRNALeu2 transcribed in vitrohad little difference, but only one fourth that of the modified ones. It was found avariant(LeuRS-A) of Escherichia coli LeuRS carrying a 40 residue-long duplication in its connectivepeptide 1 (CP1) domain has a 3 fold lower specificity for tRNALeu1 than for tRNALeu2, whereasthe native enzyme had the same specificity for their isoacceptors. By in vitro generation of aseries tRNALeu mutants we found that the difference on the first base pair in the acceptor stemsof the two tRNALeu isoacceptors lead to the different rates of leucylation catalyzed by LeuRS-Aand the flexibility of the acceptor stem of tRNALeu might play a key role in its recognition bythe synthetase.
Key words： tRNALeu; leucyl-tRNA synthetase; interaction
Li Yong , Wang Enduo . Study on the Interaction Between Leucyl-tRNA Synthetase and tRNALeu from Escherichia Coli[J]. Journal of University of Chinese Academy of Sciences, 2003 , 20(1) : 117 -122 . DOI: 10.7523/j.issn.2095-6134.2003.1.019
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